Open-wire-testing instrument.



C. L. PARIES. OPEN WIRE TESTING INSTRUMENT. A' PPPPPP TI NNNNNNNNNNNNNNN 0.

7 Patented J an. 13, 1914. v s EEEEEEEEEEEE 1.

' I II 5 (U L L Fc mlgs WITNESSES: INVENTOR. f

[0. L. FARIES.

OPEN WIRETESTING INSTRUMENT. 'APPVLIOATION FILED JUNE 29, 1910.

1,084,542. Patented Jan.13,1914.

S'SHEETSLSHEET 2.

\Jne

iu T 1 lmml nw b J I I F7 3 fihmkg QQ VoociBfi WITNESSES: INVENTOR adWham @041,

v 0. L. BABIES. OPEN WIRE TESTING INSTRUMENT.

IIIIIIIIIIIIIIIIIIIIIIIIII 0.

1,084,542. Patented Jan. 13, 1914.

. a SSSSSSS SHEET 3.

L'm E wmmm EEEEWWE D @hQYK kee ad les INVENTOR.

WITNESSES:

v 4A QAJJD; @411,

3 TN TL I T F N 1 UNITED STATES PATENT OFFICE.

cnAiaLss LEE EARIES, or PHoNEroN, 01110.

ornn-wmnrssrmer I STRUM NT,

To all whom, it may concern: M

Be it known that I, C ApnEsJJEE Farms, a citizen of the llnitcd States,residing at Phoneton, in the county of Miami and State of Ohio, haveinvented an Open-\Vire'lesb the break or open located-within sufiicient'nearness, and it will be particularly adapted to'th'e testing. oftelephone aerial wires. I

attain these objects, by the combination of electrical apparatus and thewiring of the circuits connecting same, as illustrated in theaccompanying drawings, in which-- Figure '1,- shows at A, a small directcurrent motor on the armature shaft of which is a double ringcommutator, each ring having three segments offconducting materialinsulatedfrom each other, and from the shaft; each ring being in contactwith three brushes, one at the top, and one at each side, so

about forty-five degrees from a perpendicular line if drawn throughcenter of shaft. At B, is an adjustable capacitybox made up ofcondensers, ranging in capacity from. 0125 to 2. mfds,eachcondenser'asiconnected to a brass disk. and these'disks are placedalong" the side of fa brass strip, in such a manner, so they can beconnected to it by the insertion, of a splitbrass plug between the disksand the strip. The condensers are coir nccted to the two rowsof tendisks, in the following sequence; reading from right to left, condensercapacities, .0125, .025, .05, .l, .2, .5, .75, 1.. 2., 1nfds.,makingatotal of 9.875 nifds. At (1,, and C is a rheostat in which theresistance coils range from 1. to. 5000., ohms, arranged' in r thefollowing order; reading from tlig r ight side of C toward the left,resistance coils are connected be tween the twelve disks in the folowingsequence,resistances 1., 1., 2;, 2., 3., 3., 5., 10., 20., 30., 40.,ohms, thence from the left side of (1,, to the right, resistance coilsare connected between the twelve disks, in the following sequence;resistances, 50"., 100., 200., 300., 4:00, 500.,'1000.,'2000., 3000.,4000.,

v5000. oh is, makinga total resistance of .l6,067..ohm At K, a pushspring key,

Specification of Letters Patent.

the function of which is to open two contact points and to close'twoother contactpoints, upon being pressed down. At S is a startingrheostat for the motor. At S 8,, S 3,, and S are one lever two pointswitches, for making contacts in circuits as shown and as hereinafterdescribed. At T,, and T are terminal jacks for the insertion of wire orconductor which is to be tested. At T is a terminal. jack for theinsertion of a battery tap. At T and T are terminal jacks for theinsertion of the iVheatstone bridge arms 0 and (1, respectively. At Tand T are terminal jacks for the insertion of a ground wire. At T,,, andT are terminal jacks for the insertion of the voltmeter leads. At D, isa \Vheatstone bridge and shunt galvanometer. At E, is a battery,

Patent-ed Jan ..'13,-1e1i.

I Application filed June 29, 1910. Serial No.1 569,622. w i

preferably a sixty volt storagev battery. At

V, is a double reading scale voltmeter. Fig. 2, is' a simpler form ofthe instrument, in which the motor and ring commutators are replaced bytwo telegraph relays,

shown at A, with front and back contacts for their armatures, theserelays being vibrated'in unison, the action of a small voltage sounderor buzzer with a vibrating armature, shown at A in an open and closedcircuit. These two telegraph relays can either be vibrated as shown, oran alter- Hating orpulsating current can be used for this purpose, ifdesired, if of a low frequency by connecting same to the relay circuit.Theresistance rheostat C and C the switches S S S 3 ,36, the terminaljacks T and T are omitted and terminal jack T,,, added in thisinstrument, terminal jack T is added for the insertion of a smallbattery'tap as shown. Switch S closes the circuit which operates thesounder or buzzer, which in turn, vibrates the twov relays in unison,through the action of contactin relay circuit, which is carried onarmature of sounder or buzzer, andis opened and closed by same.

Fig. 3, is the same as Fig. 2, except that the two telegraph-relays arereplaced by one vibrating relay, shown at A.

a The switches shown' in these drawings,

would preferably be platinum contact lever keys, and, the terminalcontacts can be terminal posts, or soldered. contact clips, but wereshown as drawn, for simplification of detail.

Method of operation fReferring to Fig. 1 1, one end of the wire orconductor which is broken. open between two testing" stations,

and which it is desired totest, for location of break, is inserted at T;A tap from a ,(30 volt battery, having the opposite polarity tapgrounded, is inserted at T,,. A- Wheatstone bridge, withshunmgalvonometer,-D,- the arms 0, and d, of-which are inserted at T andT respectiyely, and having the I woint rounded either direct as shown 2g a a or through a telegraph relay for small impedance. A double-readingscale voltmeter V, having the leads from same inserted at T and T Aground wire is inserted at T and 1' The switch S is thrown to theleft alittle more than is shown, or open,

" s in contact with ground, where broken, the

' galvano'meter needle will be deflected to one side, on account of thedifference in the potential of .the two grounds connected, one at thebroken wire, and one at point 0 This difference of potential will causea current to flow, fi'om'ibreak to Wire; to top brush on ring of, theinner commutator;- thence to left hand brush of same ring; to

bridge arm 0, (bridge arm a, and galvan ometer-bridgearm b in multi e)to point a, or reverse, thus deflecting needle to one side or the other.The battery is disconne'ct-ed 'for this'test. As the needle responds tovery minute currents, the resistance of the ground'atbreak can be veryhigh or very low and the same result be obtained.

This will be the effect generally in the United States, the groundpotentials at different points, even shd'rt distances apart, areaffected by the numerous 'electr1cal opera- ,Ltion of traction'railwa-ysand power stations in the middle lVestern States.

'tion of wire can be verified in another way,

using ground to one potential, especially so The condiif no deflectionis shown, as is explained later.

The ideal condition of wire for a test, is

'when no deflection of needle is shown. Thiscondition can be obtained ina majority of cases of opens, either from one end of the wire', or fromthe other, onac nt of wires ar a 'pole, than r breaking more frequentlythe middle of a section, thus leaving oneend I of the wire in the air,and the other end on the ground. VVhen-the wire is iii-this conditiontests can be taken by instruments shown in Figs. 1, 2, and 3,-while,when w1re is in contact with ground at the break,xa-

- test with instrument shown in Fig. l, only can be taken, except asexplained later by "usinglvheatstone bridge resistance rheostat inarm d,separatezfrom bridge.

"is made 'as follows A- test of a wire or conductor showing nodeflection on'galvanometer needle, when in I strument is connected up asdescribed above;

Switch S is now thrown tothe right, this starts the motor revolving fromright to left, gradually increasing in speed as current in motor circuitis increased by the cutting out of repressed down, this breaks thecontacts 0011-, necting the two right hand brushes to bridge sist ancein switch S Key K, is then arms 0, and d, and closes the contacts, whichputs the two right hand brushes in contact with the positive terminal ofbattery E, this battery having its negative terminal grounded. Thepotential of battery E, causes a current to flow through right handbrushes; to segment of rings; toytop brushes; thence to wire orconductor; and to capacity-box B, in multiple, then upon revolution ofcom- Inutator, the right hand brush contacts with segments, are broken,and segments immediately make'contact with left hand brushes, whichallows the charge, which is now held by wire and capacity box, 'todischarge through the two sides -of*the bridge to ground at' 0, as therevolution-of motor is very rapid, this discharge through bridge isalmost continu0us.- As the charge held y than thgt held bycapacity box:none of the condensers being plugged in, part of this and the needle canbe brought to rest on center, by plugging in enough condenser capacityin box B, to or conductor.

The sum of the capacities required in box, to balance the needle, whentesting a Wireor conductor broken open between testing stations, whichequals capacity of wire or conductor from testing station to the open,when compared with the capacity of a wire or conductor of the samecharacteristics, open at the distant station, (tested and found in thesame manner) will be proportionate to their respective lengths. Thusshowing the length of defective wire or conductor from.

testing station to the open.

hen arms a, and b,'of bridge are equal, then I a AC=Bx and a where A=length of unbroken Wire, B=capacity. of, unbroken wire, C=capacityplugged in box,-i. e. capacity of near portion of brokenfwire, w=length.of broken w-i're testing 'stath n to break.

tested, is very small, the following verification of condition of wireqr conductor should the 'wire' or conductor, is much larger charge willflow across galvanometer from. arm a, to arm 6, deflecting needle to oneside, I

equal capacity of wire i vIf the capacity ofwire or conductor being. i

be made throw switch S to upper contact, switch as shown, switch S toleft hand" contact, thus putting grounded battery E direct to'wire -orconductor, through volt- 5 nneter V,.the deflection of voltmeter willthen show condition of insulation resistance of 'wire brcondu'ctoijincase the wire or con;

ductor was incontact with ground at the break. and there being nodifference in the ground potential of the two grounds, the galvaiiometerneedle would fail to show the true condition of wire or conductor; butthe fact of so little capacity being shown, would indicate that eitherthe greater part of the charge was escaping through. a. ground-con tactat break, or that the open was very close to testing station, and ifthe" voltmeter shows high insulation resistance on the wireorco-nductor, the second conclusion of open being near testlngstation, canbe taken as true,

\ capacity .of' wire or conductor is known [It would be presumed thatinduction on the'wirebeing tested, picked up from adj oining' j vires,would afi'ect the galvanometer needle, but on wires that are transposedaccording to latest methods, by telephon com-, panies, this is not thecase the need e remairiing almost perfectly steady on center, whencapacity ofwireor conductor and bozjr are-equal, probably the needlebeing shunted to,its smallest current. is too slow in action,

'to respond to any of the small induced cur.-

Ano'ther suppjo-f rents which flow across it. sition would be that thequicker dlscharge of the box, would affect the needle before the wire orconductor discharge which is held back by the resistance of the wire orcon; ductor, thus. giving two impulses to the needle, but in fact theneedle is affected only ance rl1eostat' (l,, and 0 can beso arranged andthat one plug will cut in the specified amount resistance and capacitydesired, but this is not necessary in the above test.

Very small capacities can be accurately lntilSHlIfl l byproportioning'the bridge arms and 7), 10 to 1 respectively, theresulting capacityplugged in box to obtain a balance onnecdle will thenhave the same ratio to Elie wire capacity as (.1, arm has to 6, arm. 0Making arm a, 100 ohms and arm lo, 19 ohms, then M where a: a rm ofbudge, 6:; I) aim of wire or conductor, can be made by throwing switch Sto upper cont-act,sw1tches S and .S,, asshown, deflection of voltmeterwill 'then' show any diiierence of potential between a possible groundat break, and the groundat. 0, and the direction of current flow can beobtained.

The test as described above for wire 01;

conductor having'a good insulation resist}.

ance to the break, can also be taken'on a wire",

.or conductor, when wet weather conditions. I

thayeccaused a distributed leak on the wire; this condition is found onmost. telephone companies? wires toy-day, the practice being to maintainaninsulation resistance of10 megohmsper mile in dry weather. I o

" The ratio of the capacityof a broken wire,

' to the capacity of an unbroken wire, of the" same characteristicscorresponds to their length. Tests have been made withithis instrument,where the deflection on a voltmeter in series with an unbroken wire,opensixtyfive miles distant. showed forty volts, toa battery voltage ofsixty through voltmeter to ground; and good results obtained.

Instrumentshown in Fig. 2 is used as describedabpve for Fig.1, the onlydifference. as will be seen, being that the armature of one telegraphrelay is connected to the wire or conductor. at T and the armature ofthe other telegraph relay is connected to the capacity box B, they bothaccept a charge from batteryE', upon pressure of key K,;.from the frontcontacts, and, then discharge through the back contacts, to tiii twosides of the bridge to ground at point 0, thus performing the samefunction as commutator on motor shaft A Fig. 1. A smallvoltage tap istaken from battery E, and inserted 'at T.;,, which, upon closing switchS Fig. 2, operates the sounder A on an open and closed circuit, which inturn vibrates the two telegraph relays in unison by action of contact onsounder armature which is inlrelay circuit. As front contacts of relaysare 'eonnected to the same bridge arms as the back contactof the samerelay until the key K, is pressed, the galranolneter needle is ready torespond to any current picked up from the wire, up't'o thetime it] isaffected by the discharge produced by pressure of key Kyeither withrelays vibrating or at rest; The same arrangement is made in Fig; 1. asboth side brushes on each- .ring are connected to the same arm of bridgeun" keyK, is pressed down. If alt-ernating or pulsating current is usedfor thevibratlon of the two telegraph relays, the relay circuitwill beterminated at T... and on an additional jack, not shown, and the vibrating Soundefand its circuit will omitted.

- operation here is-by one vibrating relay A,-

The instrument, shown in Fig. 3, can be used for the testdescribedabove, vbnt the with the necessary contact points, which performthe same functibn as A, Fig. 1, and A, and A, .2 as will be readily seenfrom drawing. The two instruments,

shown in Fig. 2, and Fig. 3, arefmuclr construction, and

simpler and cheaper in they are designed principally for making thetest'described ab'ovb, although the motor and commutator' shown inFig.-1, will be more reliable,'on account of the liability of the relayarmatures Fig. 2, not vibrating in perfect unison, which would tend tothrow a false deflection on galvanometer needle, although, this can bereadily detected by the sound ofthe vibrating relays; thecontact.'points of vibrating relay Fig..' 3, must also be kept adjustedso the armature contacts strike both points on the one side at the sametime, or the same defect will be shown.

Another method .of' testing a wire or conductor, showing high insulationresistance, 1s to insert one end'of an unbrokenwlre,

open at distant testing station at T and to.

insert one end ofthebroken Wire at T Figs. 1, 2, and 3, then thecapacity which it is necessary to plug in capacity box B. to balance thegalvanonieter needle, when bridge arms a, and b, are equal, will havethe'same ratio to the capacity of the unbroken wire, (taken as describedabovel' as the length of broken'wire, from break to distant testingstation, has to the length of unbroken wire'between testing stations.

'first described? where A length of unbroken wire,B= capacity ofunbroken wire, C:capac1ty plugged in capacity box to balance needle,

Y length of broken wire, from break to distant testing station. i

This will show short however on accoun of the decrease of potential ofcharging battery as distance increases from testing station, betterresultsbeing obtained by testough there is a shortage alsoshown wit t onlong wires, it is muchsmaller, and as man making the tests be;

comes familiar with the wire capacities un= der different weatherconditions, it will only be necessary for a-test tobe made on the wirethat is broken taken as first described toenable person making test tosend repair man within short distance of the break.

A. testis made with instrument show inv Fig.1 when wire-to be tested isin co act with ground a e-follows: After the tru- VVhen bridge arms a,and b, are equal,"

ratus as described in first test,'this' condition current flowing.Ifthis' is not aflpotential through the opposite sides of thelVheatstone bridge in the same direction.

switch S to right hand contact, and adjust the resistance in 'rheostat C[and C by 1nserting split brass plugs, until galvanoinet'er amount ofcurrent-flowing from battery E, through rheostat C :andC then'ce temp;brush on capacity box ring of commutator, thence to left hand brush, tobridgearm 6, and b, to ground at f0 "as is flowing through wire, to topbrush on wire ring of commutator, thence toleft hand'brush, to bridgearm 0' and a to ground at 0.

and back again from changein grot'uid potential. Throw switch S startingmotor. re- \'0lving, then upon pressing key K down the wire orconductor, and the capacity box of their capacity discharges throughbridge to ground will affect the gal z'inorneternee' le the box to makeanequal capacity discharge as is being received from the wire; Thiscapacity will be proportionateto the capacityof voltmeter taken fronbattery to wire, for

top contact, switch S5, to left hand contact, switch S, to left handcontact, plus aidefiection of voltmeter taken from wire to 'switbh S totop contact, switch S to left hand contact, and switch s, to right handcontact; 5, being a deflection of voltmeter taken from; battery-toground through bridge, by throwing switch S, to top contact, switch S toright" hand contact, switch S, to left hand contact, 6,, being thedifference of the above two deflections. The charge to wire and thedeflectionshown to wire are both cutfdown by the 1 ground otential, andas 8 is not affected by 1t, we a d the ground potential to deflectionment is connected to wireand other of wire will be apparent from the'galVan-I ometer needle beingde flected to"one. side," by action ofcurrentsefiupbydiiference'in potential of ground, at break and at 0 asdescribed before. Throw switch ,130 top, 'cont'act, switch S and.S,, asshown,then' voltmet-er will show potential of ground which will causethe flow of -a fcurrent through the ,corresponding :sidef'of theWheatsto'ne bridge in;the s'am'efdirection N that which would becausedfby battery? E, to flow through the other side Of'theWheRt-l stonebridge, the battery connections are charged so that the two currentswill flow the wire would sh0w, i'f open at break,'.i n the] same ratioas 8 15 to 5 5 be ng a deflection Then throw switch 55,, back to lowercontact,

needle is balanced bnflcentr, bya'n equal 7 Needle will probably swingslowly off center will be charged as before, andthe difference l as akick to one side, which can be elimi natcd by plugging in condensercapacity in leak to ground,' by throwing switch S 10 V ground, forground'potential, by throwing to wire to obtain 8,, this being theactual deflect onto wire, if noground currentwas flowing, thus keepingits ratio to 6 thesame as is the leak to the whole charge. That is,

as the voltmeter resistance isso high; that the wire resistance itself,and the resistance through bridge to ground,'-haveno appreciable efiecton the deflections, these two deflections 5 and 8,, practicallyrepresent that part of the charge: which escapes at break, and the wholedischarge which would return through bridge to ground, if wirewas openat break, respectively, and the difierence between the two deflections 8would therefore represent that part of the charge which actually-doesreturn from the wire when same is grounded through resistance at break.

Hence the ratio and v G 8,=C6,, a

' C 8, I O

and as i AG=,B:v, as in firsta-tes't, then A 3 Ba:,

and

;AC6 B5 where A=length of unbroken wire between teststations, B-capa-cit of unbroken wire between test stations, wire would show ifopen and clear at break, m length of broken ,wire test station to break,C =capacity discharge of--',brol en' wire through bridge to groundequaledby capacity pluggedfrirr 'boX,:,8 ,=V oltmeter de fleet-ion towire, .tplusdefiectionshown for ground potential", f5,woltineter-defiection i to ground through bridge, e difference of abovetwodefiection'sfi I If C is very smallfit may not affect thegalvanoineter needle appreciably inthis-case the bridge a'rnns'a, and b,will have to be proportioned 10, to '-1.' respectively,- and thls willnecessitate re-adjustment 'qf resistance in rheostat C, and'C Fig. 1,to-balance the galvanometen needle oncenter again, before attemptingtotake the test,vwh'en this is done the needle will respond to thepressure of key K by a kick to one side, until balanced on center byplugging in capacity, n box.

:capacity, broken,

The capacity plugged in box will then be ohms, then I I v ,11) {1702 01and M i, v I i c a 92 V-L a and as before i -C162 a: then I 5 a 53andas: m

AO=B2:, as in first test, then A as =Bx,

and

i' AI C 6 s m whereA=len th of unbroken wire between I (i. e. 10 ohms,)og=voltmeter deflection to wire, plus defieetion'shown for ground p0,-

, tent-ial, o rzvoltmeter deflection to ground through bridge, 8=difference of above two deflections.

V This test, on account of the. small capacities handled, is a.moredelicate test than the first test, and probably will not be so oftenused, although, as good results were obtained withit, and it furnishes ameans of locating a break on a wire or conductor which .iS broken openand grounded through un- .known resistance, thus filling 'a demand for atest, which at the present time is not filled, I believe it will besuccessfully used, and of great benofit- This test could be taken withinstruments shown-in Figs. 2 and 3 if the bridge "circuit was arrangedso the resistance rheostat in arm .6' could be cut out'and-used in laceof C and G Fig. 1,;and voltmeter deli ection taken to wire and to groundhefore instrument was j'utup for test, but one of the objects in gettingthis instrument out was to furnish an instrument for use with 4 otherinstruments connected'as they are in general use in testing wires. Sothe instru- I ments shown in Figs. 2 and 3 'will probably Only be usedfor first test.

The time when these instruments will be most needed, is in very coldweather when bad, it is very desirable to locate trouble, in

order to use the quickest method of transportation to get the repairmanto the. break.

" While I have illustrated and described the preferred construction forcarrying my invention'into efi'ect, this is capable of variation ormodification without departin from the spirit of the invention. I thereore do not wish to be limited to the exact details of construction setforth but desire to avail myself of such variations and modificatlons ascome within the scope of the appended claims; I p Having fully describedmy invention, what I claim as new and desire to secure by Letters Patentis: g I

:1. Anelectri'cal device fo determining the relative capacities of twoelectrical conductors comprising in combination a Wheatstone brldgec1rcu1t including a known capacity in one arm thereof, an unknown caandrapidl pacity connected in the other arm thereof,

and means forsimultaneously, automatically rectly to t e electromotiveforce and then immediately and simultaneously discharging saidcapacities through the resistance arms of saidbridge or the opposite. 2.-An electrical device for determining the relative capacities of twoconductors comprising a testing device including 'tw o,.re

sistances, a current detecting device. connected to each resistance, andaswitch interposed between the detecting device and'the two capacitiesto be compared whereby the capacities will be rapidly, simultaneouslyand alternately. charged from an electronictive force and thendischargedthrough said resistance, the current pulsations throng theresistances being unidirectional.

3. An electrical device for determining the relative capacities of twoconductors comprising a testing device 'i'ncluding two ...resistan ces,aj current detectin'gQdevice conv nected. to eachf'iesistance, andmeans" si-' I multaneously; automatically and alternately:

charging the conductorsfrom an electromotive force and'then dischargingsaid conductors throughsaid resistances, the current pulsations throughtheresistances being unidirectional.

41 An instrument. of the classdescribed comprising a Wheatstone bridge;a con 7 denser; a conductor to betested; and means 11.j- An instrumentof the class des ribed connecting'said capacities di- W through saidarms.

for alternately charging-bath condenser '65 and said conductorindependently of said W'h'eatstone bridgefand connecting said co'ndenser and conductor inopposite arms of said bridge and permitting.theirj discharge 5. An "nstrument of the l class described comprising aWheatstonebridge a' variable condenser; a conductor tobe tested;anddenser and said conductor independently of-r 1 said Wheatstone bridgeand connecting said means for "alternately charging said'con condenserand conductor in opposite arms of said bridge and through said arms.

6. An instrument of the class' described comprising. a Wheatstone=bridgef; a condenser; a conductor to be tested; and means :Eoralternately charging both said-condenser comprising a Wheatstonebridge;'a variable through said arms tothe' and saidconductor-independently of said Wheatstone bridge andconnecting' saidcon- 85 denser and conductor opposite arms" of said bridge andpermitting their discharge through said arms to the ground. 7. Aninstrument of the class described condenser; a conductor to be tested;and means for alternately charging said condenser and said conductorindependently of said VVheat-stone bridge and connecting said condenserand 'conductorin opposite arms of said bridge and permitting theirdischarge ground. I

8. An instrument of the class described comprising a Wheatstone. bridge;a condenser; a conductor to be tested; a variable resistance in serieswith said condenser; and means for alternately charging both saidcondenser and said conductor independently of said Wheatstone bridge andconnecting said condenser and conductor in opposite arms of said bridgeand permitting their discharge throughsaid arms. 5 v 9. An instrumentofthe-class described riable resistance in series'with said condenser; andmeansffor alternately charging both "said condenser and said conductorin:

dependently of said bridge'and jcdnnecting said condenser and conductorin opposite' arms of said bridge and permitting their condenser; aconductor to be tested;.'a va- 1 20 riable resistance in series'withsaid condenser; and means for alternately charging both said condenserand-said conductor independently of said=bridge and connecting saidcondenser and conductorin opposite r25 arms ofsaid bridge and permittingtheir dis-- charge through-said arms to the ground.

permitting their discharge comprising-a Wheatstonebridge; a variable,condenser; a conductor'fto be tested; a ya- 11'0 throughQsaid arms.

through said arms.

' through said arms to the ground.

insane 'means for. alternately charging said unbroken wire and both saidwire to be tested and said condenser independently of said Wheatstonebridge and connecting saidunbroken wire and said wire to be tested andsaid condenser in opposite arms of said' bridge and permitting theirdischarge 12; An instrument of theclass described comprismg alVheatstone bridge; avariable condenser; anunbroken strung wire open;

at a distant station; a wire who tested connected in-parallel with saidcondenser; and means for alternately charging said unbroken wire andboth said wireto beztested and said condensefhidfifidriiitly of said,VVheatstone bridge and connectingsaid nrbroken wire and said wire to betested and said condenser in opposite arms of sa1d brldge and permittingtheir discharge 13. An instrumentof the class described comprising aVVheatstone Bridge; a condenser; an unbroken s trun wireopenat a distantstation; a Wireto be tested connected in parallel with said condenser;and means for alternately charging said unbroken wire and both said wireto be tested and said condenser independently of said Whea tstone bridgeand-conneeting-said un-W broken wire and said wire to be tested and saidcondenser in opposite arms of said bridge and permitting their discharge14:. An instrument of the class described comprising a Wheatstonebridge; a variable condenser; an unbroken strung wire open at a distantstation; a wire to be'tested cOh-= nected in parallel with-saidcondenser; and means for alternately charging said unbroken wire andboth said wire to. be tested and said condenser independently of said-Wheatstone bridge and connecting said unbroken wire and said wire to betested and said condenser in oppo'siteq arms of said bridge andpermitting their discharge through said arms to the'ground,

An instrument of the class described comprising a lVheatstone bridgehaving both of its ratio arms grounded; a variable condenser; a motor;commutator rings connected with said motor';-a brush adapted to beconnected with a conductor to be tested and contacting with one of saiftrings; a brush contacting with the other ring and connected with saidcondenser; a battery having one end grounded; brushes connecting theother end of said battery with each of said rings on one side of saidfirst m'entioned-brushes; and brushes connecting the different arms ofsaid bridge with the different rlngs on the otherrside'of sa'd firstmentioned brushes, substantially as described;

y 16. An instrument of the class described. Q

comprising a Wheatstone bridge having both of its ratio. arms grounded;a condenser; a variable resistanfde in series with said condenser; amotor; commutator rings connected with saidmotor; 'a brushkadapt ed tobe connected with a conductor to be tested and contacting with one ofsaid rings;

a brush contacting with the other ring and connected with saidcondenser; a battery having one end grounded; brushes connectingtheother end of said-battery with each of said' rings on one side of saidfirst mentioned brushes; and brnshes connecting the "different arms ofsaid bridge with' the dif-' ferent rings on the other side of said firstmentioned brushes, substantially as described. I v- 17. An instrument ofthe class described comprising a Wheats'tone bridge having both itsratio arms grounded; a varia ble condenser; a galvanometer arranged insaid .bridge; a motor; commutator. rings coniiected with said motor; abrush adapted to be connected with'ea-conductor tobe testedandcontacting with one of said rings; a

brush contacting with the other ring. and.

connected with said condenser; a battery having one end grounded;brushes connectiijnglhenithenend ofr.said---batterywitheach of saidrings on one side of said first men- 'tioned brushesrand brushesconnecting the diiferent arms of said bridgewith the .dif-

ierent rings on the other side of said first mentioned 'brushessubstantially as described.

.18. An instrument of the class described.

comprising aVVheatstone bridge having both a galvanometer arranged insaid bridge; a resistance in series with said condenser; a motor;commutator rings connected with said motor; a brush adapted to beconnected with a conductor to be tested and cdntacting with one of saidrings; a brush contacting with the other ring and connected with saidcondenser; gmbattery having one end grounded; brushes connecting theother end of said battery w th each of said rings on one side of saidfirst mentioned brushes; andlnushcs connecting the different arms ofsaid bridge with the different rings on the other side of saidment'ioned brushes, substantially as described.-

19. An instrument of the class described having botlrot its ratio armsgrounded and denser a rariab'le resistance in each arm; a variable andcontacting wfithione of said rings; a

tionedbr ushes; and brushes connecting the difi'erent arms of saidbridge with the dif-' i'erent rings on the other side of said firstmentioned brushes; substantially as de;

scribed. g

, 20; An instrument of the class described comprising a \Vhe'atstonebridge having both of its ratio arms grounded and a variable resistancein each arm; a variable condenser; a. resistance in series with saidcondenser; a motor; commutator rings connected with said motor; a brushadapted to be connected with a conductor to be tested a and contactingwith one of said rings; a

brush contacting with the other ring and connected with said condenser;a battery having one end grounded; brushes connecting the othenendof'said battery with each ofsaid rings on'one side of said firstmentioned brushes;and brushes connecting the different arms of saidbridge with the different rings on theother side of said first mentionedbrushes, substantially as de. scribed. I g Y 21. An instrument oftheclass described nectedwith said motor; a'brush adapted to be connectedwith a conductor to be tested 'and contacting with one of said rings; a

brush contacting with the' other ring and connected with said condenser;a battery having one end grounded; brushes c0nnecting the other endof'said battery with each of said rings on one'side of said firstmentioned brushes; and brushes conn cting the different arms of saidbridge Witi the different rings on the other side of said firstmentioned brushes, substantially as described. 1 i I CHARLES LEE FARIESQWitnesses: i Q i WILLIAM WALTER WA'r'r,

CHARLES VVELooN .BELL.

Copies 01th patent may be obtained for five cents each, by addressingthe Commissioner 51 I'atentl, 4 v Washington, D. O.

